A program that can secretly change your dialup connection setting so that instead of calling your local internet provider, your PC calls are routed to an expensive 0900 or international phone number.
A premium-rate phone dialler providing access to porn sites. Known to be installed by the RapidBlaster parasite, possibly also ActiveX drive-by installation.
Open a DOS command prompt window (from Start->Programs->Accessories) and enter the command (for Windows 95/98/Me):
"%WinDir%\SYSTEM\regsvr32.exe" /u "%WinDir%\System\DialerOffline.dll"
Or, on Windows NT/2K/XP:
regsvr32.exe /u "%WinDir%\System32\DialerOffline.dll"
You can then delete the 'DialerOffline.dll' file inside the Windows System folder, and whatever dialler connections are using it - in the specimen I tested this was a 'LiveGirls' desktop icon and a folder 'C:\blankdialer', but this may vary.